Elemental distributions within multiphase quaternary Pb chalcogenide thermoelectric materials determined through three-dimensional atom probe tomography. (August 2016)

• Record Type: Journal Article
• Authors: Yamini, Aminorroaya; Li, Tong; Mitchell, David R.G.; Cairney, Julie M.
• Is Part Of: Nano energy. Volume 26(2016:Aug.)
• Page Start: 157
• Page End: 163
• Publication Date: 2016-08
• Subjects: Thermoelectric materials -- Sodium -- Dopant -- Atom probe tomography -- Segregation -- Solubility; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2016.05.019
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Nanostructured multiphase p-type lead chalcogenides have shown the highest efficiencies amongst thermoelectric materials. However, their electronic transport properties have been described assuming homogenous distribution of dopants between phases. Here, we have analyzed elemental distributions in precipitates and matrices of nanostructured multiphase quaternary Pb chalcogenides doped to levels below and above the solubility limit of the matrix, using three-dimensional atom probe tomography. We demonstrate that partitioning of sodium and selenium occur between the matrix and secondary phase in both lightly- and heavily-doped compounds and that the concentrations of sodium and selenium in precipitates are higher than those in the matrices. This can contribute to the transport properties of such multiphase compounds The sodium concentration reached ~3 at% in sulfur-rich (PbS) precipitates and no nano precipitates of Na-rich phases were observed within either phase, a result that is supported by high resolution TEM analysis, indicating that the solubility limit of sodium in PbS is much higher than previously thought. However, non-equilibrium segregation of sodium is identified at the precipitates/matrix interfaces. These findings can lead to further advances in designing and characterizing multiphase thermoelectric materials. Graphical abstract: Highlights: Sulfur-rich precipitates contain higher concentration of Se and Na than the matrices in multiphase quaternary Pb chalcogenides. Partitioning of sodium occurs between matrices and precipitates for compound with sodium concentrations both above and below solubility limit of the matrix. Nonequilibrium segregation of sodium occurs at the matrix/precipitate interfaces. The sodium solubility limit of PbS is higher than previously considered 2 at%.